Electronic pipes



June EU, 1%? J. MARKOWITZ ELECTRONIC PIPES Filed May 18, 1964 W NM 5 5 ATTORNEYS.

United States Patent 3,327,044 ELECTRONIC PIPES Jerome Marlrowitz, Allentown, Pa., assignor to Allen Organ Company, Incorporated, Macungie, Pa., a corporation of Pennsylvania Filed May 18, 1964, Ser. No. 368,119 12 Claims. (Cl. 84-101) This application relates to a new improved means for electronically generating musical tones. More particularly, it relates to a means for electronically duplicating the tone produced by pipe organs or similar musical instruments.

Heretofore, electric or electronic musical instruments, such as organs, have produced musical tones by generating an electric signal, amplifying the signal, and applying it to a loudspeaker. The electric signal is electronically shaped so as to cause the loudspeaker to generate a tone substantially like that produced by the musical instrument being simulated. While systems are available which are capable of producing musical tones closely approximating those produced by pipe organs, in the opinion of many, substantial distinctions still remain.

It has been determined that these distinctions between electronic organ tones and pipe organ tones can be attributed to the inherent quality of the loudspeakers used to transduce the amplified electric signal into sound and to the means by which these loudspeakers are coupled to the air. That is, the loudspeakers, because of their structure and manner in which they are used, tend to color the musical tones they produce, so as to prevent them from precisely duplicating organ pipe tones.

It therefore is the general object of this invention to provide a novel tone generating device that produces a tone which is indistinguishable from that produced by an organ pipe.

It is another object of the present invention to provide a novel tone generating device that duplicates wind organ sound yet retains many of the advantages found in electronic organs.

It is another object of the present invention to overcome the tonal deficiences found in electronic organ loudspeakers.

It is yet another object of this invention to provide a novel tone source which produces the precise sound equivalent of an organ pipe.

It is still another object of this invention to describe a means for producing the exact electronic analogy of pipe organ sound.

It is a further object of this invention to provide a means for duplicating pipe organ tones which is competitive in cost.

Another object of this invention is to provide an electronic organ tone generator which provides satisfactory tonal intensity, without the use of any electronic amplifier.

Other objects will appear hereinafter.

For the purpose of illustrating the invention, there are shown in the drawings forms which are presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.

FIGURE 1 is a schematic diagram of an electronic organ pipe in accordance with this invention.

FIGURE 2 is a perspective view of a modified electronic pipe in accordance with the present invention.

FIGURE 3 is a modification of the schematic diagram shown in FIGURE 1 using twoelectronic pipes.

FIGURE 4 is a perspective view of a modification of the electronic pipe shown in combination in FIGURE 1.

FIGURE 5 is a perspective view of another modification of the electronic pipe.

In the subsequent description of this invention, only a basic electronic tone generating device will be described. It is to be understood that in a full size organ a plurality of such devices, together with modifications to provide certain tonal qualities to the output sound, will be used. The actual number of tone generating devices and modifications thereof will be determined by the type of instrument to be constructed and can be readily ascertained by those skilled in the art. So as to avoid unnecessarily complicating the description of the invention, and because the electronic tone producing devices are well known to those versed in the art, the methods and procedures for connecting the several tone generators in the chromatic groups and wiring them to the keyboards and coupler arrangements will not be described.

Referring now to FIGURE 1, wherein like numerals indicate like elements, there is shown an electronic tone generator designated generally as 10. Generally, electronic tone generator 10 comprises an oscillator for developing an electric signal at a predetermined audio frequency and a loudspeaker for transducing the electric signal into a musical tone.

As shown, the oscillator comprises a transistor 12 connected from its collector terminal through the parallel connected inductor 14 and capacitor 16 to its base terminal. The base terminal is also connected to resistor 18 which in turn is connected to ground potential. The emitter circuit of the transistor 12 consists of a series connected emitter resistor 44, loudspeaker 40 and base resistor 30'. Connected as described, the subject comprises a transistor type Hartley oscillator. The manner in which an oscillator of this type functions is known, and therefore need not be described in detail.

Power to energize the oscillator is supplied by direct current source 20 and random noise generator 22. When key 24 is depressed closing contact 26, random voltage is impressed upon transistor 12 through keying resistor 28 and base resistor 30. The function of the noise generator 22 is to add air sound and random motion to the ultimate sound. This is one of several devices available for aiding in the production of all the tonal elements which are present in the sound of an organ pipe. A more detailed explanation of the function of the noise generator 22 may be found in U.S. Patent 2,989,886. The noise generator 22 may be of a type similar to model 901A manufactured by Grason Stadler Company of West Concord, Mass.

A single pole double throw switch 32 provides a means by which noise generator 22 may be taken out of the circuit. That is, power source 20 may be connected directly to key 24 through shorting wire 34 by means of switch 32. Capacitor 36 and resistor 38 provide a filter by means of which the higher frequencies from noise generator 22 are passed to ground. The combination of keying resistor 28, capacitor 36, and resistor 38, also function to provide proper speech characteristics for the oscillator.

Loudspeaker 40 is mounted in the bottom of resonator 42. As indicated above, it is connected in series in the emitter circuit of transistor 12. Thus, when key 24 is depressed, closing contact 26, transistor 12 will oscillate at a frequency determined by the value of the resistance, capacitance, and inductance of the Hartley oscillator circuit. The oscillating signal generated in the emitter circuit will pass through loudspeaker 40 and cause it to generate a tone at the oscillation frequency. The tone thus generated can be adjusted by varying the value of the circuit elements (e.g. the capacitance of capacitor 16) until the tone produced is at a frequency corresponding to a musical note.

It should be noted that the signal applied to loudspeaker 40 may be modified in several ways to cause the tone generated to approximate the tone of an organ pipe. The air sound produced by noise generator 22 as described herein is one example of a means to modify the tone generated. The prior art teaches others. See for example U.S. Patent 2,989,886.

It has been found that even though the electronic circuit generating the signal applied to a loudspeaker 40 includes all of the known wave forming means by which pipe organ sound is approximated, the sound produced by electronic means still does not quite duplicate the sound of an organ pipe. It is believed that the reason for this discrepancy lies in the inherent qualities of the loudspeaker itself (especially when operated at a substantial volume level) and the method of coupling the loudspeaker to the air.

To overcome the discrepancies between the loudspeaker sound and pipe organ sound, and thus produce a precise electronic analogue of pipe organ sound, loudspeaker 40 is mounted in the end of resonator 42. As shown, resonator 42 is an elongated column which may be square in cross-section and open at the end opposite the speaker 42. Resonator 42 may be fabricated from any suitable material such as wood, metal or plastic. Different tonal results of course, will be effected depending upon the material used. Further, its cross-sectional shape may be made round, rectangular or polygonal, if desired. Changes in design of the pipe, of course will effect the tonal quality thereof. The precise construction of resonator 42 need not be described in detail, because the proper resonator may be readily constructed by those familiar with the centuries old art of organ building.

It is also to be understood that the design of the loudspeaker itself will also affect the ultimate sound which is produced by the electronic pipe. On the other hand, since only a single musical tone and its harmonics and individual transients are passed through one loudspeaker, it is possible to use the inherent coloring characteristics of various loudspeaker as a means of producing desired tonalities. In other words, certain tone qualities may best be produced by using a speaker with poor high frequency response while on the other hand, a wide range speaker can be used for producing a different tone or stop.

The length L of resonator 42 is chosen to have a value equal to any integer times /2 the wave length of the tone generated. This value is generally referred to as the resonant frequency of the resonator. Tonal variations can be accomplished, to a degree, by varying the length of the pipe. For instance, a brighter tone can be achieved by using a half or smallerwave length resonator in the same way that pipe organ builders do.

When the loudspeaker 42 generates a tone at the resonant frequency, the combined effect of the speaker and the resonator will be to produce a precise analogue of the sound generated in an organ pipe. That is, the tone emanating from the combination of the speaker and resonator will be in-distinguishabe from the tone that emanates from an organ pipe. If the tone generated from loudspeaker 40 is at the resonant frequency of resonator 42 the system operates at high efiiciency, possibly approaching 100%, eliminating need for an amplifier.

It is to be understood that exact resonance may, in manufacture and adjustment, be difficult to achieve. By resonance, therefore, it is meant that the electronic pipes are substantially resonant. It is also possible to color the tone by intentionally keeping the pipe off resonance. It is within the scope of the invention, therefore, to operate some of the notes in this manner.

In FIGURES 4 and 5 there is shown two other practical resonator arrangements. The resonator configurations 80 and 90 are similar to other resonators, such as resonator 42 shown in FIGURE 1. However, in FIGURE 4, loudspeaker 82 is mounted in the side of the resonator 80 closely adjacent one end thereof. In FIGURE 5 the speaker 92 is mounted on the side of the resonator 90 at the middle of the resonator.

The arrangements of speaker and resonator shown in FIGURE 4 as compared to FIGURE 1 is that of convenience of mechanical configuration. The arrangement shown in FIGURE 5 will also resonate at a sub-harmonic, providing economy of space which is applicable in the production of certain tonalities. This assumes that one end of either resonator 80 and 90 is closed. If neither end is closed, or if both ends are closed, different resonant frequencies will be achieved. The tone produced by either of the pipes shown in FIGURES 4 and 5 is substantially the same. However, it is usually more convenient to mount the speaker adjacent one end of the resonator.

In electronic organ art the same speaker is often used to generate more than one tone. In other words, several oscillators, tuned to different frequencies, may be connected to the same speaker. It has been determined that when more than one signal of relatively close frequency are simultaneously impressed upon a given loudspeaker, a form of distortion results. Analysis indicates that the distortion is caused by the close coupling of the several signals on the single speaker diaphragm or cone. This type of distortion is especially noticeable in the lower audio frequency ranges. On the other hand, if two signals are applied to individual closely adjacent loudspeaker, only acoustic coupling takes place and the distortion created thereby is not apparent, even in a lower frequency range.

It has been found that since distortion will be minimized even though the individual speakers are closely adjacent, it is possible to use a single resonator for more than one loudspeaker.

Referring to FIGURE 2, there is shown a resonator 60 constructed in the same way as resonator 42 of FIGURE 1. However, in FIGURE 2 resonator 60 has three loudspeakers 46, 48 and 50 mounted at one end thereof. For this purpose, a specially constructed mounting board 45 has been provided. The mounting board 45 comprises triangular end walls 52 and 54 and angularly disposed side walls 56 and 58. Loudspeaker 46 is mounted in end wall 52 and loudspeakers 48 and 50 are mounted in side wall 56 in a conventional manner. Each speaker is connected to a separate audio frequency generating means (not shown).

The mounting locations of the speakers are a matter of structural convenience and if their location is relatively equivalent along the length of the pipe, only minor losses in efiiciency will result because of such location differ ences. As shown, the same resonator can be used for several loudspeakers. It should be pointed out that although three loudspeakers are shown in FIGURE 2, it is within the scope of this invention to use more or less loudspeakers.

The main advantage of the multiple loudspeaker structure shown in FIGURE 2 is that of compactness. There may be a certain loss of efficiency and performance, however, this must be weighted against the space economy which is achieved.

Referring now to FIGURE 3, there is shown another embodiment of the invention. To simplify the description, components similar to those shown in FIGURE 1 have been given the same but primed numbers. In FIG- URE 3, the circuit diagram shown is the same as that in FIGURE 1, except a second loudspeaker 62 has been coupled into the collector circuit of transistor oscillator 12. A shorting switch 64 has been connected across the loudspeaker 62'. When the shorting switch '64 is closed, loudspeaker 62 is effectively taken out of the oscillator circuit. In this condition the circuit does not difler from that shown in FIGURE 1.

When shorting switch 64' is open, loudspeaker 62 is coupled into the collector circuit for producing tones in accordance with the wave shape of the signal in the collector circuit. Tests have shown that the wave shape of the electric signal present in the collector circuit is different than that in the emitter circuit. That is, although the signal is at the oscillation frequency it will cause the speaker to produce a note with a different tonality.

The difference in tonality can be of a sufficient degree to permit the tonal output of speaker 62 to represent another organ stop. Thus the output of speaker 40' in the emitter circuit may produce a flute-like tone and the loudspeaker 62' in the collector circuit may produce a diapason or string sound. The precise adjustments to be made in the oscillator circuit so as to emphasize the desired difference in the tones between the emitter and collector circuits are well within the skill of those versed in the art.

Loudspeaker 62 is shown mounted in the end of the resonator 66'. Resonator 66' is similar to resonator 42', in that it will interact with the tone produced by loudspeaker 62' to produce a tonal output that is indistinguishable from the tone produced by an organ pipe. The structure of resonator 66 may be somewhat modified to help emphasize the particular stop that it is to simulate.

In some cases the loudspeaker 62 may not be mounted in a resonator 66'. Thus, if the power or tonal quality of the tone generated by speaker 62' per se is such that it varies only an insignificant amount from the tonal qualities of an organ pipe or its difference is indistinguishable among other tones being simultaneously produced, loudspeaker 62 may be used without a resonator.

It is also possible to connect loudspeaker 62 into the emitter circuit in series with loudspeaker 40. Loudspeaker 62' would be mounted in a different type of resonator to produce the tonal variations equivalent to a stop different from that produced by resonator 42'. The disadvantage of coupling loudspeaker 62' into the emitter circuit is that when it is selectively switched in and out of the circuit there is a marked increase or decrease in the power output of resonator 42. This problem can be overcome by means of complicated compensating circuits. However, the simpler solution is, as described, to couple the loudspeaker 62 into the collector circuit. Loudspeaker '62 should be of such impedance that it will be coupled to the oscillator in as efiicient a manner as possible and still not materially affect the operation of the transistor oscillator 12'. When this is done, loudspeaker 62' can be selectively turned on and oif without materially affecting the operation of resonator 42. It has been found that for best ope-ration the impedance of speakers 40' and 62' should be between 50 and 100 ohms.

When the above described invention or its modifications, with their inherent multi-stereo characteristics is incorporated into an electronic organ together with means for electronically producing the air sound, and random variations, the tone produced by such an instrument cannot be distinguished from that produced by a pipe organ. This assumes, of course, that electronic means have been provided to make the timbre or tone quality and speech of the various notes similar to organ pipes. The means for producing such effects are known, and need not be described in detail.

Since the cost per note of a system using the above described invention is comparable or lower than the cost of organ pipes, it is possible to construct an electronic organ with each note being a separate entity, and yet the cost of such a system would be competitive with that of a pipe organ. In addition to being competitive, the electronic organ would provide advantages in flexibility, tone quality, ease of maintenance, and size.

Rather than construct an electronic organ in which each note is produced by an electronic pipe comprising a speaker mounted in a resonator, an economically attractive package would be to produce an organ which uses electronic pipes only in the more critical louder tonal areas and standard electronic organ tone producing means in less critical, softer areas. It has been determined that, in general the discrepancy between standard electronically produced tones and organ pipe produced tones are most noticeable in the more powerful sounds. Therefore, if the portions of the electronic organ used to duplicate the more powerful sound are provided with electronic pipes in accordance with this invention, and the balance of the instrument is left as a standard system, the overall effect produced will still be that of a tone indistinguishable from pipe organ tones.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification as indicating the scope of the invention.

I claim:

1. An organ tone producing means comprising a plurality of loudspeakers for selectively transducing audio frequency electric signals into audio frequency tones, a resonant column tuned to a frequency relatively close to the frequency of said audio frequency tones, and mounting means for mounting said loudspeakers adjacent an end of said resonant column, said loudspeakers being mounted relative to the end of said resonant column so that said resonant column resonates at the frequency of the tones transduced by said speaker.

2. A tone generating means for a musical instrument comprising a single electronic oscillating means for generating audio frequency signals at a predetermined frequency, a first loudspeaker means connected to said oscillating means for transducing one of said electric signals into an audio frequency tone at a frequency of said electric signals, a second loudspeaker means selectively connected to said oscillating means for transducing another of said electric signals into an audio frequency tone at a frequency of said electric signals, and a resonant column resonately associated with said first loudspeaker means, said resonant column being tuned to a frequency of said audio frequency tone.

3. A tone generating means for musical instrument in accordance with claim 2 wherein a resonant column tuned to an oscillating frequency of said oscillator is resonately associated with said second loudspeaker means.

4. A tone generating means for musical instrument in accordance with claim 2 wherein said electronic oscillating means is a transistor oscillator, and said first loudspeaker means is connected in series with the emitter circuit of said transistor oscillator, and said second loudspeaker means is connected in series with the collector circuit of said transistor oscillator.

5. A tone generating means for musical instrument in accordance with claim 4 wherein a resonant column tuned to the oscillating frequency of said oscillator is resonately associated with said second loudspeaker means.

6. A11 electronic organ comprising a plurality of generator means for generating electric signals at a plurality of predetermined audio frequencies Wave shapes and powers, key means associated with said generator means for selectively initiating said generator means, a plurality of loudspeaker means for transducing generated electric signals into audio frequency tones, and a resonant column means resonately associated with each of those loudspeaker means which produce the relatively more powerful audio frequency tones.

7. Electronic organ tone generating means comprising a transistor oscillator means for generating an electric signal at a predetermined. audio frequency, electrical power means for providing energy to energize said transistor oscillator means, key means for selectively apply-' ing said energy to said transistor oscillator means to cause it to generate said electric signal, loudspeaker means connected in series with the emitter circuit of said transistor oscillator means, and resonant means tuned to said predetermined audio frequency, said resonant means being resonately associated with loudspeaker means.

8. Electronic organ tone generating means in accordance with claim 7 wherein a loudspeaker means is selectively connected in series With the collector circuit of said transistor oscillator means.

9. An electronic organ tone generating means in accordance With claim 8 wherein a resonant means tuned to said predetermined audio frequency is resonately associated with the loudspeaker means connected in series with the collector circuit of said transistor oscillator means.

10. An electronic organ comprising a plurality of generator means for generating electric signals at a plurality of predetermined audio frequencies, Wave shapes and powers, key means associated with said generator means for selectively initiating said generator means, a plurality of loudspeaker means for transducing generated electric signals into audio frequency tones, resonant column means resonantly associated with said loudspeakers, at least one of said resonant columns being resonantly associated with more than one loudspeaker means.

11. Tone generating means comprising only one electronic generating means including an oscillator, a transducer for converting electric tone signals produced by said oscillator into acoustic signals, saidtransducer being connected only to said tone generator, and a resonating column tuned to a frequency of the acoustic signals produced by said transducer, said transducer being coupled to said column.

12. An electronic pipe comprising one electronic gen erating means including an oscillator, a transducer for converting electric tone signals produced by said oscillator into acoustic signals, said transducer being connected to said tone generator, and a resonating column coupled to said transducer.

References Cited UNITED STATES PATENTS 2,619,866 12/1952 Bailey 18131X ARTHUR GAUSS, Primary Examiner.

D. D. FORRER, Assistant Examiner. 

2. A TONE GENERATING MEANS FOR A MUSICAL INSTRUMENT COMPRISING A SINGLE ELECTRONIC OSCILLATING MEANS FOR GENERATING AUDIO FREQUENCY SIGNALS AT A PREDETERMINED FREQUENCY, A FIRST LOUDSPEAKER MEANS CONNECTED TO SAID OSCILLATING MEANS FOR TRANDUCING ONE OF SAID ELECTRIC SIGNALS INTO AN AUDIO FREQUENCY TONE AT A FREQUENCY OF SAID ELECTRIC SIGNALS, A SECOND LOUDSPEAKER MEANS SELECTIVELY CONNECTED TO SAID OSCILLATING MEANS FOR TRANSDUCING ANOTHER OF SAID ELECTRIC SIGNALS INTO AN AUDIO FREQUENCY TONE AT A FRE- 